In minimally-invasive therapeutic procedures, many of the tools that are used are designed to pass through a channel within a flexible endoscope, i.e., to fit within a lumen and be advanced to the distal end of the flexible endoscope. The endoscope is able to provide an image that the medical practitioner views while employing the tool to carry out the function for which it is designed. The general concept in designing the therapeutic tools that are currently used in such procedures is to make them compatible with available flexible endoscopes, which means that the tools must be substantially smaller in cross-sectional size than a flexible endoscope and must be configured to be usable when passed through the working channel contained within the flexible endoscope. This constraint on the size of the tools that can be used in minimally-invasive procedures tends to limit the types of tools that can be used and also makes the task of using such tools more difficult. It is likely that various types of diagnostic or therapeutic devices that might otherwise be used to treat a patient undergoing a minimally-invasive procedure would be of use in such procedures if not for the size limitation and other problems with use of the device while it is fitted through the working channel of an endoscope.
Accordingly, it would be desirable to develop a different approach that would enable various types of medical tools to be used in a minimally-invasive procedure, but without requiring that they be sufficiently small in size to pass through a conventional endoscope. Such tools are sometimes used to carry out a function at an internal site that is being separately imaged with an endoscope, but that approach typically requires another incision be made for the tool so that it can be passed transcutaneously into the patient's body and then advanced to the desired site where it will be employed. A catheter or conduit might be used for inserting a tool into an internal site, and it may be useful to provide an alternative approach for imaging the path followed by the catheter or conduit. A new approach should give greater emphasis to the use of a tool, a conduit, and/or a catheter within a patient's body, rather than to imaging at the site using a conventional endoscope. To achieve greater versatility in the use of tools, catheters, and conduits, it would be preferable to achieve a different approach to imaging an internal site either at the distal end of such devices or slightly proximal of the distal end. The imaging required to provide a visual field where the device is being used should be provided by means other than a conventional endoscope. It should be possible to image from behind the distal end of a device, as well as at its distal end. Furthermore, it should be possible to provide stereo images of a site where a tool or other device is being used internally without employing an endoscope. Stereoscopic images can be particularly useful because they provide more information about depth when using tools at a site.
It would therefore also be desirable to produce multiple images at disparate positions on one or more tools or components, since the multiple images can be employed to expand a limited field of view that is available from only a single image and position. Also, it would be desirable to use these images to view portions of a site that would otherwise be obstructed, if viewed from only a single position, as well as to view a site with the perspective provided by images created at disparate sites. A further desirable function would be to employ images made at different wavebands of light to extend the information about a site that is provided, relative to that provided by only a single such image.
To minimize costs and provide more efficient operation, it would also be desirable to enable a plurality of different imaging probes that are provided on tools and/or other devices so that they can share or multiplex share light source(s) and other components that are used to produce images of a site. Clearly, it would be more cost effective to share a base station that includes one or more light sources and image processing capability, with a plurality of imaging devices disposed on one or more tools or other components. In some cases, it may be desirable to share the same waveband of light produced by a single light source, which is shared by multiple imaging devices. Images might be produced by imaging devices either serially or in parallel. In other applications, it may be desirable to supply light from a plurality of different light sources and in different wavebands to a plurality of imaging probes disposed at the distal ends of tools or other components, for imaging an internal site.
The benefits of providing a system capable of imaging from multiple positions on one or more tools or components, and using the same base station is clearly not limited to medical applications. There are many other applications and environments for using imaging technology that can also benefit by providing imaging of a site from the distal end of one or more tools or components, such as a robot's end-effector, and from a plurality of locations on the one or more tools or components that share light source(s) and processing.
One concern that arises when plural imaging devices are used to image a site at the same time, for example, when producing a three-dimensional (3-D) image is that there can be substantial image noise due to illumination crosstalk. In this case, the two images used to produce the 3-D image are provided by two imaging devices that are spaced apart from each other a known distance, but scan almost the same area of the site. If scanning optical fibers are used to produce each of the images, they will scan an illumination spot over the surface at the site. The reflection from these spots is captured to produce each successive pixel of the respective images derived from the output signal of each scanning device. However, the reflection from the spot illuminated by one scanning optical fiber can be detected by the other imaging device, which can produce the crosstalk problem that causes poor image quality. Accordingly, it will be important to minimize crosstalk between different imaging devices that are scanning overlapping areas of a site.